»«« PALEONTOLOGY OP NEW- YORK. 



Platyceras uii^ruiforuie ( n. 8.)- 



Plate LIX. Via. 1, 2, 3 & 4. 



Shell oblique, arcuate, subspiral : volutions one or two, more or less 

 contiguous at the apex ; last volution angular, extending in a nearly 

 straight or slightly curved direction towards the aperture : aperture 

 oblique subovoid ; peristome sinuous. 



Surface longitudinally plicate, and marked by fine crowded undulating 

 lamellose striae. 



The specimens which I have referred to this species present some variety of form 

 and surface marking; and it is not impi-obable that the examination of a larger 

 number of specimens may prove that there are two distinct species, one having 

 more numerous plications than the other. 



Fig. 1 a, 6, & 2. Views of young individuals of this species. 



Fig. 3 a. Profile view from the dorsal side, showing the spire and the broad flat plications. 



Fig. 3 6. View of the upper side of another specimen, with more numerous plications. 



Fig. 4 a, var. multicarinatum. View of the lower side of a specimen which has numerous 

 narrow plications. 



Fig. 4 b, c. Views of the upper sides of similar specimens. 



Geological position and locality. In the shaly limestone of the Lower Helderberg 

 group : Albany and Schoharie counties. 



Platyceras dilatatnni ( n. s.). 



Plate LIX. Pio. 5 a - t, & 6 c. 



Shell obliquely depressed-conical, with a single minute contiguous vo- 

 lution at the apex, below which the shell expands very rapidly, 

 particularly on the lower side, while a subangular ridge may be traced 

 from the apex nearly to the base : aperture subcircular or transversely 

 broad-oval ; peristome undulated by the more or less numerous plica- 

 tions of the surface. 



SiTRFACE, in the yoUng shell, marked by obscure transverse striae and more 

 conspicuous longitudinal striae ; while in the older shell the right side 



